What seems to be a natural addition to the next generation of mice is apparent in Apple's MightyMouse™ [10] in which two pressure buttons are available on each side of the mouse. Although, pressure based input is featured in many digitizers and TabletPCs and has been widely studied [3,11,15,16], little is known about the limitations to pressure based input using a mouse. This lack of knowledge may explain why the pressure buttons available on the MightyMouse™ do not supply continuous pressure values and operate similar to a two-state button. One possible reason is that there is not sufficient knowledge on the limitations and benefits of a pressure augmented input with a mouse.
Designers can naively augment a mouse by adding a pressure sensor to a fixed location on the mouse. This approach, while providing an additional input dimension to most mouse-based interactions, can also be limiting. The location of the sensor may not be appropriate for interacting with some of the major features of a mouse, such as clicking. Additionally, a poorly augmented mouse would restrict users to a limited number of pressure levels [11,15]. Furthermore, selection mechanisms would be limited to the current methods for selecting pressure values, such as quick release or dwell [15]. Finally, a simple augmentation may not facilitate bi-directional pressure input (where pressure control starts at 0 and moves to a higher pressure and the reverse).
Understanding the limitations and benefits of pressure based input with a mouse can allow designers to augment the mouse with pressure sensors (FIG. 1) and utilize the augmented device in a variety of novel contexts. To effectively harness the potential of a pressure augmented mouse designers need to know where to mount the pressure sensors on the mouse, create some mechanisms for controlling pressure input, and identify methods for selecting a pressure value.